30 Days
by Center of the Galaxy
Summary: Slight AU. It was supposed to be simple: watch Princess Serenity for 30 days while her mother deals with problems on Saturn, but the League never expected that this moon princess would test their patience and yet somehow worm her way into their hearts.
1. A Deal

_**Author's Note: **__What can I say? I love __**Sailor Moon**__ and I love __**Justice League**__and I have always wanted to write something about them. This idea has been rattling around in my brain for awhile and I finally had time to write it out. I know the concept seems odd, but please give it a try! A little side note, because both Serenity and her mother are named the same thing, I have decided to call Princess Serenity, Sere as a nickname. That way no one will get confused! This is also slightly AU. Let's just pretend that the Silver Millenium never really ended and has continued into present time. Endymion and his kingdom never exsisted. Everything else is canon and the same. Thanks and please enjoy! _

"We don't do babysitting," The Batman growled. "Period."

The conference room was silent and Diana let her gaze drift to the Queen who sat across from them. She kept her gaze cool and betrayed no hint of emotion in her grey eyes. Her silver hair—almost the color of moonlight—jostled slightly as she ran a pale hand through it. The golden moon crescent gleamed as it caught the light and Diana repressed a smile. Her indifference reminded Diana so much of her own mother. How many times had her mother stressed the importance of remaining calm even when facing the toughest of obstacles? It was interesting to see that this woman knew the tricks of royalty as well.

"My Queen, let me—" One of the guardians stood—a young woman with cropped blonde hair and radiant blue eyes—and reached down, almost as if she was going to grab a weapon.

"Uranus," The Queen's voice rang out regally in the quiet room. "Sit." The guardian did as she told and Diana glanced at Bruce. He had to know that he was about to cause a diplomatic disaster and that was the last thing the League needed to tangle with.

"Queen Serenity," Diana said, her voice full of kindness. "What Batman meant to say was that the League does not take on protecting jobs. It divides our team's focus and doesn't make us as helpful as we could be to the people of Earth."

"I understand your fears, Wonder Woman," The Queen told her with a small smile playing on her lips. "But I am not asking you to sacrifice all of your time. I only need a month—just thirty days." Diana glanced at Bruce but his expression had not softened and he still appeared as resolute as before.

"And I said we don't babysit, your majesty," Batman growled and Uranus looked ready to kill him. The Queen smirked and simply tilted her head to the side. "I mean no disrespect, but you don't need our help as many people do."

"True," Queen Serenity conceded. "But have I not helped your League out once or twice before?" Bruce didn't say anything but Diana knew the Queen was right. Many times the Queen had leant her power to them and had taken care of some valuable research on threats from other planets. She had even given J'onn a temporary home on the Moon while the civil war was fought on Mars. If anything, the League was heavily indebted to Queen Serenity.

"You have," Bruce mumbled. "But having your daughter here would hinder League business."

"Batman," The Queen interjected. "My people have guarded Earth and the solar system from countless threats for many millennia. I have never asked for your League's assistance before and I have never hindered you." The Queen's voice softened. "I am asking you, please, let my daughter stay with you."

"If I may," Diana interjected. "Why are you asking for our assistance now?" The Queen shot a glance to Uranus who nodded before speaking.

"Her majesty's presence has been requested on Saturn," Uranus explained. "It would appear that Beryl—a radical with many followers—has begun to stage a coup and the princess of Saturn has asked for aide."

"I see," Diana remarked. "But why not let your daughter stay on the moon?"

"Sere has . . ." The Queen smirked and let her voice trail off. "I am taking all my guardians to help and there would be no one to watch my daughter. Besides, I would fear that without anyone to watch her, she would run off to Earth."

"And that is bad?" Diana questioned, a bit intrigued.

"My daughter is next in line to be queen," Serenity explained. "And as such, she must learn that her place is on the Moon watching over the Earth and not being on it." Her expression clouded a little and Diana could see she was worried. "I thought that maybe if she stayed with your League and was a bit closer to the Earth and saw all the problems that go on, she would finally learn her place."

"Well," Diana began. "Your majesty, you must give us time to talk to the other League members and—"

"We have no time!" Uranus shouted, which earned her a disproving glance from her Queen. "The Princess needs to be moved now or Beryl will succeed!"

"Uranus," The Queen hissed. "Be silent!"

"I beg your pardon, your majesty, but I cannot!" Uranus slammed her hands on the table and her face twisted up in pain. "Please, I beg of you, take our Princess and keep her safe!"

"Uranus!" The Queen growled. "I order you to sit and be silent." Uranus reluctantly did as she was told, but the damage was already done. Diana was positive that there would be no changing Bruce's mind now, even if the other League members did support this idea. His mind was set.

"Fine," Bruce spat out as he stood and Diana couldn't believe it. Had the Batman actually changed his mind? "But only for thirty days." The Queen rose and smiled. It was a radiant thing to see and Diana realized that the Queen had truly been worried for her daughter's safety.

"I shall bring her to you tomorrow," Queen Serenity promised, trying to compose herself. "I cannot thank you enough."

"No, it's fine!" Diana insisted. "We are glad to be able to help you."

"Your majesty," Batman said coolly as he bowed and then promptly exited.

"Please don't be offended," Diana pleaded. "Batman is just always like that."

"I could understand his concerns," The Queen conceded. "But I am relieved that we were able to see eye to eye."

"Queen Serenity," Uranus interjected quietly. "We must go."

"Of course," The Queen said with a dismissive wave. Turning to Diana, she grinned. "I shall bring my daughter to you tomorrow morning."

"Good," Diana replied. "Have a safe trip back."

Queen Serenity smiled before departing out the doors. Diana sighed and stared out the huge window. She could see the Moon from here and could faintly make out the castle. What was this Princess of the Moon was like? Would she be kind or timid?

Regardless, it would be interesting to have a teenager amongst them—even if it was just to see that hopelessly frustrated look on Bruce's face.

_**Author's Note: **__Reviews would be greatly appreciated! _


	2. Day 1: Arrival

_**Author's Note: **__I know, this is an odd story with an odd concept but I know someone must be reading this story hence the new chapter. But seriously, if anyone is reading this, please review! I love to hear feedback about my work! Please enjoy!_

_**Day 1—8:30 am **_

Princess Serenity forced her expression to remain neutral and calm as she and her mother—accompanied by the four inner guardians—entered the Justice League's Watchtower. She couldn't allow her mother or the League to see how she excited she was about staying here. Besides, if her mother caught wind that her daughter was planning to visit Earth with the League as her "guardians" she was positive her mother would march her back to the Moon.

"Sere," Queen Serenity began, her voice soothing and calm. "I want you to not trouble the League in any way. They have done us a huge favor, taking you in, and I do not want them to wish they hadn't, is that understood?"

"Yes, Mother," The young princess replied. "I shall do my best." Her mother smiled—a rare show of affection—and wiped a wisp of blonde hair out of her daughter's face.

"And please Sere," The Queen pleaded. "Please be safe." The princess grinned and pulled her mother into a hug. Her mother stifled a gasp and returned the hug.

"Mother, you be safe too," Princess Serenity mumbled. "Promise me."

"Princess," Sailor Mars met her gaze and Princess Serenity could see in her fiery eyes that the guardian of the flame would protect her mother. "There is no need to worry."

"You see, Serenity," The Queen began congenially. "I will be in good hands."

The door opened and a woman in a startling red, gold, and blue outfit appeared. She had long flowing raven hair and radiant blue eyes. As she walked over—red boots clicking on the floor—the young princess saw a golden tiara with a red star in the middle resting on her head. Princess Serenity forced herself to remain calm despite the fact that she was unsure what to make of this woman.

"Queen Serenity," The woman bowed her head slightly and the Queen smiled in returned. "I trust this is your daughter." A hand was pressed on Princess Serenity's back and with a glance at her mother, Serenity stepped forward.

"I am the Crown Princess of the Moon," She began in customary greeting. "Princess Serenity and I thank you for your kindness."

"Wonder Woman," The woman replied, holding out her hand and Serenity cautiously shook it. "Pleased to meet you, your highness."

"Sere," Her mother met her gaze and Serenity could see a hint of sadness in those familiar eyes. "I shall return in thirty days. Behave."

"Yes, Mother," Princess Serenity replied as she curtsied. "Have a safe trip and return victorious." Her mother gazed at her for what seemed like an eternity and the princess wished to say so many things—I love you, don't die, don't go—but she had been taught better than that. She wouldn't betray her mother's teachings just because she was frightened.

And then, without another word, the Queen left, her guardians trailing behind her.

"Don't worry, Princess," Wonder Woman's voice startled her, but Serenity smiled. "Your mother seems quite the valiant warrior and I don't doubt her return."

"Sere," Wonder Woman seemed confused.

"What?"

"You may call me Sere," The Princess explained. "It's a nickname. I am called it on the Moon so I don't get confused with my mother." Wonder Woman grinned and pushed open a door.

"Come," She called. "Let's introduce you to the rest of the League."

As Serenity entered further into the Watchtower, she couldn't help but feel excited. Sure, she was worried about the crisis on Saturn, but for the first time, she was alone to do as she wished. And with the tower being this close to Earth, there was no way Serenity was going to miss a chance to go visit her favorite planet.

Now, if she could just figure out a way to slip out unnoticed . . .

_**Author's Note: **__Hit that review button! You know you want to . . . _


	3. Day 1: Reflection

_**Author's Note: **__I love this chapter and I hope you do too! Please enjoy! _

_**Day 1—9:00 PM **_

Serenity smiled as she took in the surroundings of her room. In one corner, there was a small desk with a wooden chair. On top of the desk was stationary and Serenity grinned. It would seem that she would be able to contact her mother after all. There was a huge window that let her gaze upon the Earth whenever she wished and a small bed placed by this huge window. There were pale white curtains, but Serenity knew she didn't need them. She would never tire of staring at the Earth.

She had to get there—somehow, the Crown Princess of the Moon knew she had to visit. Sighing, she plopped onto her bed and stared upward at the cool metallic ceiling. She had met the Justice League earlier and Serenity let her thoughts drift back to that first meeting.

_"May I present her highness," Wonder Woman said, presenting Serenity with a wave of her hand. "Princess Serenity of the Moon." Serenity curtsied and let her blonde hair fall in front of her face, obscuring it slightly._

_"I thank you for taking me in for these thirty days," Serenity replied with a forced smile. "I shall do my best to keep out of your way." _

_"We are pleased to have you, Princess," A man with a huge, red "S" told her. As he stood, his red cape swished to the left and Serenity wondered who he was. She had seen him visit the Moon once before. "I'm Superman." Recognition filled Serenity's eyes. _

_"I remember you!" She exclaimed in a very un-ladylike manner. "You visited us five years ago and asked for Mother's assistance." Superman grinned and nodded his head._

_"Your mother was very helpful," He informed her. "Now, shall I introduce you to everyone else?" Serenity nodded. "You already met Wonder Woman." The woman beside her nodded her head and grinned. "This is Batman." An imposing man sat next to Superman, his mouth set in a hard frown. He was scary and frankly, it didn't seem like he wanted to be here right now. The dark colors of his costume made his blue eyes seem like a sea during a storm and Serenity wondered what he had seen in his life. _

_"Your highness," He told her with forced gentility. "Please don't interfere too much with our work." The remark earned him a glare from Wonder Woman. _

_"I shall do my best," The young girl promised. "Batman, you are the one that punishes criminals with fear?" He nodded and Serenity nodded her head. Her mother had taught her that sometimes the only way to deal with criminals was to scare them into obeying your will. Thanks to her mother, no one ever committed crimes on the Moon, but Serenity had heard how crime ran rampant on the Earth, prompting the formation of the Justice League. _

_"This is Green Lantern and Hawkgirl," A man in a dark green suit waved at her and a woman with huge, white wings and clad in a golden suit smiled. Serenity grinned back and marveled at how diverse Earth's protectors were. It was proof that Earth was such a wonderful planet that it could attract so many different people to protect it. "And this is J'onn." _

_"We've met," Serenity replied. "Rei sends regards." The Martian beamed and bowed deeply._

_"It is good to see you in good health, your highness." He told her courteously._

_"You two have met?" Green Lantern questioned. _

_"I was given shelter on the Moon after the civil war on Mars broke out," J'onn explained. "Queen Serenity then sent in one of her sailor soldiers to end the war and the soldier became Sailor Mars. Since then, I have been given a home in the palace of Mars." _

_"I see," Wonder Woman muttered. Suddenly, she jerked into acute awareness. "Where is Flash?"_

_"Don't tell me he's—" Hawkgirl began threateningly when the door burst opened. Serenity felt her head snap around to see a young man dressed in a red jumpsuit with a golden lightning bolt on the front. He smirked and seemed to embody the wind as he sprinted forward. Before Serenity could even re-act, he had grabbed her hand, brought it to his lips, and kissed it. Her eyes widened and a ruby blush painted her cheeks._

_"Welcome to Earth, babe," He greeted with a confident look on his face. "Name's Flash." _

_And with that Wonder Woman had punched him. _

_Hard. _

The rest of the day had passed by uneventfully. Flash had been banished from her sight while Superman had apologized profusely for his college's actions. She had been given a tour of the tower by a gruff Batman who barely said two words to her and then she had lunch. Serenity then observed sparring sessions and was thoroughly impressed by how powerful both Wonder Woman and Hawkgirl were. Dinner had then passed with J'onn catching up since his last visit and then finally Serenity had decided to retire.

She couldn't stop thinking of the kiss that Flash had placed on her hand. On the Moon, no suitor dared to be so brazen with her. No one even came near her, thanks to both her mother and her sailor guardians. On the Moon, she was the precious princess—the girl who had to be protected. Here, she could be something different.

But then again, who was she kidding? She was from the Moon and nothing would ever change that! She would always be the girl who was untouchable, who was forbidden from leaving her ivory palace.

Any thoughts of romance—with or without Flash—would have to stop because it would never work.

Ever.

_**Author's Note: **__Well? Let me know what you think by reviewing! _


	4. Day 2: Longing

_**Author's Note: **__Found this chapter hard to write, but I really enjoy where this story is going. Please enjoy! _

_**Day 2—1:30 AM**_

_"Tell me, Princess," A voice hissed quietly. "What do you long for?" _

_ "Excuse me?" Serenity looked around and saw that no one was there. _

_ "Do you long for something, Crown Princess of the Moon?" _

_ "I demand to know who is speaking to me!" Serenity shouted, but fear gripped her. The darkness had always frightened her since she was a little child and being surrounded by it now just worried her more. Suddenly, light blinded her and Serenity looked away. When the lights dimmed, she was back on the Moon in the grand ballroom. All around her, couples swirled around her. The women's gowns were made of many different colors and as they twirled below on the floor, it looked like a little rainbow. _

_ "Do you long for balls that last until the light of the sun?" _

_ Serenity shook her head. Balls were nice, but she had never been quite fond of them._

_ "Or maybe, you simply long for someone to take your hand and lead you around the ballroom?" _

_ Serenity stifled a gasp at the thought. Her mother had never allowed her to dance with any man before and the thought in itself was both thrilling and nerve wracking. _

_ "Love, Princess?" The voice continued. "Is that what you long for?"_

_ Serenity nodded her head, though she knew it was impossible. She was of the Moon—and her mother would never allow her to pick a husband of her own choosing. Falling in love would be impossible. _

A shrill alarm filled the silence of her room and Serenity bolted out of her bed. She didn't care if she was only clad in her nightgown—even though she could practically hear her mother's voice berating her in her head—and as she sprinted down the twisting halls, she finally ended up in the main conference hall. Batman was manning the one large computer at the front of the room and barely looked up as he greeted her.

"Princess." His voice was cold and it made Serenity angry. What had she done to offend this man? Why was he being so rude to her?

"Is there something the matter?" Serenity forced her voice to come out calm and collected. She was a future queen and she would not let Batman intimidate her.

"Nothing that concerns you, your highness." Serenity thought about giving him a scathing remark, but simply held her tongue. Batman typed on the keys and ignored her. Serenity thought about going back to her room, but it was clear that she would never earn Batman's respect by doing what he wanted. If he was going to be mean to her, then the least she could do was be a pain in his side.

_Mother would kill me for this, _She thought quietly. _But if Batman isn't going to be kind to me, than why should I be kind to him?_

The alarm had ceased now and Serenity wondered if it had been a false alarm. Could the Justice League have alarm malfunctions? It didn't seem possible even though these heroes were human—well, most of them were human.

"Yo, Bats!" A red blur blew past her and Serenity shivered as a cold wind hit her. "I heard the alarm and came—"

"It was a computer malfunction," Batman explained coldly. "I fixed it now."

"A computer malfunction?" Flash echoed and then turned and saw her. His eyes widened in surprise and he quickly kneeled and took her hand. "Look, Princess, I am really sorry about earlier! I was out of line and really, I'm not like that all the time and—"

_Or maybe, you simply long for someone to take your hand and lead you around the ballroom?_

Serenity smile softly as Flash kept babbling and finally she held up her hand for silence.

"I forgive you," She told him. "I was more startled than angry."

"Oh, good, that's a relief," Flash sighed. "Cause Wonder Woman was totally pissed off at me—!"

"Flash," Batman interjected. "Princess Serenity should get some rest." Batman met her gaze and Serenity vowed that she not give him a moment of rest until he accepted her being here.

"Oh, right!" Flash explained. He smirked and bowed quickly. "Might I escort you to your room, your highness?"

"That's alright, Flash," Wonder Woman told him, stepping from the shadows. "Princess Serenity and I can walk back together." Serenity tried to smile, but instead felt sadness hit the pit of her stomach. She didn't know too much about Flash, but he honestly seemed to be the funniest guy here. He also seemed generally nice and fun to be around. Serenity wanted to spend more time with him.

_Love, Princess? Is that what you long for?_

"Until tomorrow then," Flash muttered. "Night, Princess." He sped away and Serenity couldn't help but grin.

Maybe being here wouldn't be so bad.

_**Author's Note: **__Please review! _


	5. Day 2: Plans

_**Author's Note: **__It's been awhile . . . Sorry for the delay! Please enjoy!_

_**Day 2—11:00 AM**_

"Then, what is this computer for?" Serenity asked, doing her best to keep a smug smile off her face. She had been pursing Batman all morning, asking question after question. To say that Batman was getting annoyed would be an understatement. Batman growled as he spun around and faced the teenaged princess. His eyes bore into hers and Serenity realized that he was glaring at her. His eyes scared her, but Serenity refused to look away. She would one day be Queen and she couldn't allow her fear to rule her actions.

He glared and waited for her to flinch.

She didn't.

"What do you want, Princess?" Batman hissed as he willed himself to appear even more frightening then before. He didn't understand. Criminals of the worst sort couldn't stand to glance at him and yet, this girl refused to look away. How could this be?

"Why do you hate me so much?" The question took Batman off-guard but he showed no sign of it.

"I don't hate you, Princess." He answered coolly.

"Serenity," The Moon Princess corrected. "My name is Serenity and yes, you do hate me."

"I know your name," Batman replied, his eyes finally breaking the contact and Serenity felt a surge of pride rush through her body. She had beaten the Batman at his own game. "And no, I don't hate you." Serenity raised an eyebrow curiously and titled her head in confusion.

"But you act like—"

"Princess," Batman interjected. "I have lots of things to do."

And with that, he left the room, leaving a bewildered Moon Princess behind.

* * *

><p><em><strong>Day 2—1:00 PM<strong>_

"Princess?"

"Oh, J'onn!" Serenity exclaimed, her head whipping around as she saw the Martian. He bowed slightly and Serenity smiled warmly. "You startled me."

"I apologize, your highness." He answered.

"No need," Serenity told him with a dismissive wave of her hand. She then let her gaze drift back to the huge window that allowed her to get a perfect view of the Earth. It still looked like a marble, but now that she was closer to it, Serenity could see the masses of blue oceans and green landmasses. It seemed even grander here than it did back from her palace on the moon. "I was just . . ." Her voice trailed off as she tore her eyes away from the pane of glass.

"Lost in thought?" J'onn completed and Serenity nodded.

"What is it like down there?" Serenity questioned softly.

"It's an experience," He answered non-committedly. "Earth is quite different from Mars and the Moon."

"But, it's a wonderful place, right?" Serenity persisted. "It's a beautiful place, isn't it?"

"I wouldn't protect Earth," He began. "If I didn't love it."

"Mother won't let me visit it," Serenity confessed with a frown. "She says that I need to learn that my place is on the Moon and not down there."

"She's right, your highness," J'onn told her and Serenity's face fell. "You will be Queen one day and you will have to guide Earth."

"I know that!" Serenity snapped. "Even so—"

"You'll have to excuse me, your highness," J'onn interrupted. "Wonder Woman has requested my assistance. I shall see you soon." Serenity bobbed her head and then J'onn phased through the floor. If she had telepathy and powers like J'onn, Serenity could sneak out to Earth herself and not have to worry about her mother finding out.

"If only . . ." Serenity sighed.

"If only what?" A voice asked curiously and Serenity nearly jumped as Flash appeared beside her in a red blur.

"In the name of the Goddess!" Serenity cursed as she placed a hand on her pounding heart. Instantly, Flash's face fell.

"Aw, man, I'm so sorry Sere—I mean, Princess!" His eyes held desperation and his hands failed around. It was an almost comedic sight to see him so flustered and Serenity couldn't help but chuckle. At this, Flash's curiosity piqued and he slowly titled his head in confusion. "Something funny?"

"I'm sorry," Serenity managed to say as she laughed. "It's just . . . You looked so funny!" Flash smirked and took a step closer to her.

"I looked funny?" He questioned with a small smile gracing his lips.

"You did," Serenity assured him. "And don't worry about startling me; it's a habit of mine to get lost in my thoughts." He followed her eyes and saw that she was staring at the Earth.

"You wanna go there or something, Princess?"

"Please call me Sere," She insisted. "Batman keeps calling me princess and it's driving me insane. Besides," She grinned. "I don't really think royal titles matter here."

"Alright then, Sere," He replied. "Do you wanna go to Earth?"

"Yes." She answered instantly. She was surprised she had blurted her wish out to mere stranger—someone she had known for less than two days—and yet, it felt perfectly natural to tell him all this. She wondered why that was. Was it because Flash was the youngest member of the Justice League and therefore more relatable? Why did she feel like she could trust him completely?

"Then, why haven't you gone yet?" He questioned.

"I try!" Serenity protested exasperatedly. "But Mother disapproves and she has hindered all my attempts to get there!"

"Then, why don't I take you?"

His response took her off-guard.

"You would do that for me?" Serenity asked, surprise coloring her expression.

"Sure," Flash replied with a carefree grin. "I needed to go pick a few things in Central City anyway."

"Central City?" Serenity mumbled. "Is that where you live?"

"That's a secret, Sere," He told her with a smirk. "So, I'll just tell the others—"

"No!" Serenity exclaimed. "They'll tell Mother and I can't let that happen."

"So, you wanna sneak out from the Justice League?" He questioned and Serenity nodded her head guiltily. "Okay, then, sounds fun!"

"Really?" Serenity felt her eyes widen in shock.

"Yeah!" Flash assured her. "Alright, meet here tomorrow morning at 7:00 am. We'll sneak out right as Superman and Wonder Woman are switching monitor duty. Sound good?"

"Yes!" Serenity answered, nodding her head energetically.

"Cool," Flash told her. "See you then, Sere."

And with that he sped off into the corridors of the tower. Serenity tried to contain her joy, but felt a smile break out on her face. This had to be the most amazing day ever.

She was going to go to Earth.

Her dream would finally come true!

_**Author's Note: **I'm pleased to announce that I'm making this a Serenity/Flash pairing! Yay! Next chapter, the princess' first trip to Earth! Please review! _


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